Method And Device For Drying Clothes

ABSTRACT

A method for drying clothes in a device comprising a rotatable drum for agitating the clothes. Following a drying program, an anti-crease cycle is provided during which the clothes are intermittently agitated. Said anti-crease cycle protects the clothes from permanent creases by regularly agitating them. In order to save energy and to save the clothes and the device, the clothes are only agitated to such a degree during the anti-crease cycle that crease-formation is avoided.

The present invention relates to a method and a device for dryingclothes.

When drying laundry using a laundry dryer which comprises a rotatingdrum for receiving laundry, an anti-crease cycle is provided at the endof a drying program or a drying phase. A drying program usuallycomprises a heating-up phase, a subsequent actual drying phase and afollowing cooling-down phase. During all these phases belonging to adrying program, the drum is usually rotated continuously. This alsoapplies during the cooling-down phase when the heating is merelyswitched off. If the dried laundry is not removed immediately from thedrum at the end of a drying program, creases can be fixed in thelaundry. In order to prevent this, the drum is either rotatedcontinuously or the drum is rotated intermittently during the subsequentanti-crease cycle.

As a result of the continuous rotation of the drum or as a result of theintermittent rotation of the drum during the anti-crease cycle, thelaundry located in the drum is increasingly loosened so that no creasescan form in the laundry. The intermittent rotation of the drum isusually effected according to a fixed pattern, such as for examplestoppage of the drum for two minutes followed by rotation of the drumfor fifteen seconds. This intermittent operation continues either untilthe end of the anti-crease cycle which can last up to three or fivehours or until the time when the laundry is removed from the drum. Adisadvantage with this anti-crease cycle is that the laundry is exposedto further stress through the movement of the drum. The drive motor andthe switching elements for switching the drive motor on and off are alsofurther stressed by the continuous switching-on and off.

It is the object of the present invention to provide a method and adevice for drying laundry which has an anti-crease cycle during whichthe laundry and the components of the device are treated gently, andduring which crease formation is optimally avoided and energyconsumption is reduced.

The object is achieved with regard to the method by the features of theclaims. This object is achieved with regard to the device by thefeatures of the claims. Advantageous embodiments and furtherdevelopments of the invention are obtained from the dependent claims.

In a method for drying laundry in a device comprising a rotatable drumfor agitating the laundry, a drying program is followed by ananti-crease cycle, wherein the laundry is intermittently agitated.

Since, in the course of the anti-crease cycle the agitation of thelaundry decreases with time or since the agitation of the laundry duringthe anti-crease cycle decreases as the temperature of the laundrydecreases and/or as the residual moisture of the laundry decreases, orsince the agitation of the laundry during the anti-crease cycle isdependent on the pre-selected drying program and/or the pre-selecteddegree of drying and/or the pre-selected type of laundry, or since theagitation of the laundry during the anti-crease cycle is dependent onthe amount of laundry preset by a user and/or the amount of laundrydetermined by the device, it is achieved that the laundry is onlyagitated sufficiently during the anti-crease cycle to avoid creaseformation. As a result, the laundry is only minimally agitated orloosened during the anti-crease cycle and thus is treated very gently,whereby crease formation can be optimally avoided. Furthermore, themotor for turning the drum is switched on and off less frequently, andespecially towards the end of the anti-crease cycle, the switch-on timeof the drum movement is reduced substantially so that the components forthe drum movement such as the motor, relays for switching the motor onand off and the drum bearing are less stressed and thus the lifetime andthe reliability of the device is increased. Furthermore, energy is savedsince the overall switch-on time of the drum movement during and in thecourse of the anti-crease cycle is substantially reduced.

Since the laundry temperature and also the residual moisture is stillelevated at the beginning of the anti-crease cycle, the risk of creasesbeing fixed in the laundry is higher at the beginning of the anti-creasecycle than towards the end of the anti-crease cycle so that for optimalavoidance of crease formation, a higher proportion of agitation of thelaundry is required at the beginning of the anti-crease cycle thantowards the end of the anti-crease cycle. Furthermore, the proportion ofagitation can be optimally matched to the pre-selected drying program orto the pre-selected degree of drying or the pre-selected type oflaundry. For example, a “damp for ironing” drying program requires anoverall higher proportion of agitation than a “cupboard-dry” or “verydry” drying program. In addition, the proportion of agitation can beoptimally matched to the quantity of laundry located in the drum. Thus,the proportion of agitation of the laundry can be minimised for eachoperating state so that the laundry and the components of the device aretreated gently and the energy consumption is reduced.

In an advantageous embodiment, in order to achieve these aims theagitation of the laundry during the anti-crease cycle is thereforedependent on measured quantities and parameters which are detected inpreceding phases of a drying program and/or during the anti-creasecycle.

In this case, measured quantities and parameters which are detectedduring a heating-up phase at the beginning of a drying program and/orduring a cooling-down phase at the end of the drying program can also betaken into account.

In an advantageous embodiment in order to achieve the preceding aims inparticular, the quantity of laundry and/or the heating-up time and/orthe laundry moisture and/or the laundry moisture profile and/or thelaundry specific conductance and/or the profile of the laundry specificconductance and/or the moisture content and/or the moisture profileand/or the temperature of the laundry and/or the temperature profile ofthe laundry and/or the temperature of the drying air and/or thetemperature profile of the drying air in the drum of the dryer and/orthe comparison of the moisture content and/or the moisture profileand/or the temperature of the drying air and/or the temperature profileof the drying air in the drum of the dryer between entry into the drumand exit from the drum and/or the time before reaching a drying targetcan thus be used as measured quantities or parameters.

For this purpose, the rotatable drum has rotary movement time intervalsand stoppage time intervals in the anti-crease cycle. During the rotarymovement time intervals the drum can be turned in one direction ofrotation and/or reversingly in different directions of rotation. Theduration of an anti-crease cycle is preferably one to five hours.

In a preferred embodiment, the duration of the anti-crease cycle ispreferably divided into four time intervals wherein in a first timeinterval the proportions of agitation lie between 20% and 90%, and thatin a second time interval the proportions of agitation lie between 10%and 70%, and that in a third time interval the proportions of agitationlie between 1% and 60% and that in a fourth time interval theproportions of agitation lie between 1% and 30%.

A device for drying laundry comprises a rotatable drum for agitating thelaundry and a control device which is capable of carrying out theprocess steps and process sequences specified hereinbefore. For thispurpose, the device has a control device with an input device and atiming element. In addition, the device has sensor devices for detectingmeasured quantities and parameters, which are supplied to the controldevice and processed in the control device according to the precedingprocess sequences.

Furthermore, the device for drying laundry has a heater for heating thedrying air, a motor for driving the drum and a fan for conveying thedrying air are provided.

Further details, features and advantages of the invention are obtainedfrom the following description of an exemplary embodiment of a deviceaccording to the invention for drying laundry which is capable ofcarrying out the preceding process steps and process sequences withreference to the drawings.

IN THE FIGURES

FIG. 1 is a device for drying laundry.

According to FIG. 1, a device for drying laundry comprises a housing 1in which a drum 2 is rotatably mounted, a loading door 3, a frontbearing plate 4, an inlet duct 5 for drying air in which a heatingdevice 6 is located, an outlet duct 7 for drying air in which a fan 8 islocated and a motor 9 which drives the drum 2 by means of a belt 10.Also provided is a control device 11 comprising an input device 12 and atiming element 13. A first temperature sensor 14 is arranged in theinlet duct 5 adjacent to the inlet to the drum 2 and a secondtemperature sensor 15 is arranged in the outlet duct 7 adjacent to thedrum 2. Located on the front bearing plate 4 are two electrodes 16 todetect the specific conductance of the laundry and/or the drying air.The first temperature sensor 14, the second temperature sensor 15 andthe electrodes are connected to the control device 11 which is capableof processing signals from the sensors and the input device 12. Thedevice for drying laundry described hereinbefore can also be constructedas an exhaust air dryer or a condensation dryer.

The device for drying laundry as shown in FIG. 1 can be provided withfurther sensors such as laundry temperature sensors or the like in orderto carry out the process sequences and process steps describedhereinafter.

The process sequences and process steps described hereinafter can becarried out using the device for drying laundry described hereinbefore.

Since, in the course of the anti-crease cycle the agitation of thelaundry decreases with time or since the agitation of the laundry duringthe anti-crease cycle decreases as the temperature of the laundrydecreases and/or as the residual moisture of the laundry decreases, orsince the agitation of the laundry during the anti-crease cycle isdependent on the pre-selected drying program and/or the pre-selecteddegree of drying and/or the pre-selected type of laundry, or since theagitation of the laundry during the anti-crease cycle is dependent onthe amount of laundry preset by a user and/or the amount of laundrydetermined by the device, it is achieved that the laundry is onlyagitated sufficiently during the anti-crease cycle to avoid creaseformation. As a result, the laundry is only minimally agitated orloosened during the anti-crease cycle and thus is treated very gently,whereby crease formation can be optimally avoided. Furthermore, themotor for turning the drum is switched on and off less frequently, andespecially towards the end of the anti-crease cycle, the switch-on timeof the drum movement is reduced substantially so that the components forthe drum movement such as the motor, relays for switching the motor onand off and the drum bearing are less stressed and thus the lifetime andthe reliability of the device is increased. Furthermore, energy is savedsince the overall switch-on time of the drum movement during and in thecourse of the anti-crease cycle is substantially reduced.

Since the laundry temperature and also the residual moisture is stillelevated at the beginning of the anti-crease cycle, the risk of creasesbeing fixed in the laundry is higher at the beginning of the anti-creasecycle than towards the end of the anti-crease cycle so that for optimalavoidance of crease formation, a higher proportion of agitation of thelaundry is required at the beginning of the anti-crease cycle thantowards the end of the anti-crease cycle. Furthermore, the proportion ofagitation can be optimally matched to the pre-selected drying program orto the pre-selected degree of drying or the pre-selected type oflaundry. For example, a “damp for ironing” drying program requires anoverall higher proportion of agitation than a “closet-dry” or “very dry”drying program. In addition, the proportion of agitation can beoptimally matched to the quantity of laundry located in the drum. Thus,the proportion of agitation of the laundry can be minimized for eachoperating state so that the laundry and the components of the device aretreated gently and the energy consumption is reduced.

Consequently, in order to achieve these aims the agitation of thelaundry during the anti-crease cycle is therefore dependent on measuredquantities and parameters which are detected in preceding phases of adrying program and/or during the anti-crease cycle.

In this case, measured quantities and parameters which are detectedduring a heating-up phase at the beginning of a drying program and/orduring a cooling-down phase at the end of the drying program can also betaken into account.

In order to achieve the preceding aims in particular, the quantity oflaundry and/or the heating-up time and/or the laundry moisture and/orthe laundry moisture profile and/or the laundry specific conductanceand/or the profile of the laundry specific conductance and/or themoisture content and/or the moisture profile and/or the temperature ofthe laundry and/or the temperature profile of the laundry and/or thetemperature of the drying air and/or the temperature profile of thedrying air in the drum of the dryer and/or the comparison of themoisture content and/or the moisture profile and/or the temperature ofthe drying air and/or the temperature profile of the drying air in thedrum of the dryer between entry into the drum and exit from the drumand/or the time before reaching a drying target can thus be used asmeasured quantities or parameters.

For this purpose, the rotatable drum has rotary movement time intervalsand stoppage time intervals in the anti-crease cycle. During the rotarymovement time intervals the drum can be turned in one direction ofrotation and/or reversingly in different directions of rotation. Theduration of an anti-crease cycle is preferably one to five hours.

In a preferred embodiment, the duration of the anti-crease cycle ispreferably divided into four time intervals wherein in a first timeinterval the proportions of agitation lie between 20% and 90%, and thatin a second time interval the proportions of agitation lie between 10%and 70%, and in a third time interval the proportions of agitation liebetween 1% and 60% and that in a fourth time interval the proportions ofagitation lie between 1% and 30%. In particular, in a first timeinterval the drum agitation is switched off for 104 s and switched onfor 16 s and in a second time interval the drum agitation is switchedoff for 284 s and switched on for 16 s and in a third time interval thedrum agitation is switched off for 584 s and switched on for 16 s, andin a fourth time interval the drum agitation is switched off for 584 sand switched on for 16 s.

In a method for drying laundry in a device comprising a rotatable drum(2) for agitating the laundry, following a drying program an anti-creasecycle is provided wherein the laundry is intermittently agitated. Thisanti-crease cycle is used to avoid fixing of creases in the laundry byregular loosening of the laundry. In order to save energy and treat thelaundry and the device gently, the laundry is agitated minimally in thecourse of the anti-crease cycle so that crease formation is avoided.

1-15. (canceled)
 16. A method for drying laundry in a dryer comprising ahousing and a drum receiving the laundry and mounted for rotation withrespect to the housing, the method comprising the acts of: performing adrying program including a heating-up phase, a drying phase, and acooling-down phase; performing an anti-crease cycle having alternatingintervals including rotary movement time intervals, in which the drum isrotated to agitate the laundry, and stoppage time intervals, in whichthe drum stops rotating and the laundry is at rest, the duration of therotary movement intervals decreasing in relation to the stoppage timeintervals in response to an operating parameter.
 17. The methodaccording to claim 16, wherein the operating parameter includes thelength of time of the anti-crease cycle.
 18. The method according toclaim 16, further comprising the act of detecting the temperature of thelaundry with a sensor and the operating parameter includes a decrease inthe temperature of the laundry.
 19. The method according to claim 16,further comprising the act of detecting the residual moisture of thelaundry with a sensor and the operating parameter includes a decrease inthe residual moisture of the laundry.
 20. The method according to claim16, wherein the operating parameter includes the pre-selected dryingprogram selected by the user.
 21. The method according to claim 16,further comprising the act of receiving an amount of laundry in thedryer being preset by a user and the operating parameter includes theamount of the laundry.
 22. The method according to claim 16, furthercomprising the act of detecting an amount of laundry in the dryer with asensor and the operating parameter includes the amount of the laundry.23. The method according to claim 16, further comprising the act ofdetecting at least one of a quantity of laundry, a heating-up time, alaundry moisture, a laundry moisture profile, a laundry specificconductance, a profile of the laundry specific conductance, a moisturecontent and/or the moisture profile, a temperature of the laundry, atemperature profile of the laundry, a temperature of the drying air, atemperature profile of the drying air in the drum of the laundry dryer,a comparison of the moisture content, a moisture profile, a temperatureof the drying air, a temperature profile of the drying air in the drumof the laundry dryer between entry into the drum and exit from the drum,and a time before reaching a drying target.
 24. The method according toclaim 16, wherein the act of performing the anti-crease cycle includesrotating the drum in opposite directions during subsequent rotarymovement time intervals.
 25. The method according to claim 16, whereinthe duration of the anti-crease cycle is between about one and fivehours.
 26. The method according to claim 16, wherein the act ofperforming the anti-crease cycle includes four subsequent time intervalsstarting with a first time interval and ending with a fourth timeinterval, each time interval including the rotary movement timeintervals and stoppage time intervals, the rotary time intervalcomprising between about 20% and 90% of the first time interval, therotary time interval comprising between about 10% and 70% of the secondtime interval, the rotary time interval comprising between about 1% and60% of the third time interval, and the rotary time interval comprisingbetween about 1% and 30% of the fourth time interval.
 27. The methodaccording to claim 26, wherein the duration of the rotary movement timeinterval remains substantially the same during each of the foursubsequent time intervals and the duration of the stoppage time intervalduring the fourth time interval is greater than the duration of thestoppage time interval during the first time interval.
 28. A laundrydryer comprising; a housing; a drum receiving the laundry and mountedfor rotation with respect to the housing; a motor coupled to the drumfor driving rotation of the drum; an inlet duct providing an air flow tothe drum and a heating device selectively heating air in the inlet duct;an outlet duct receiving the air flow from the drum; a control devicecoupled to the motor and controlling rotation of the drum, the controldevice performing an anti-crease cycle including alternatingly rotatingthe drum during rotary movement time intervals and stopping rotation ofthe drum during stoppage time intervals, the control device decreasingthe duration of the rotary movement intervals decreasing in relation tothe stoppage time intervals in response to an operating parameter. 29.The laundry dryer of claim 28, further comprising a timing elementproviding a length of time of the anti-crease cycle to the controldevice and the operating parameter including an increase in the lengthof time of the anti-crease cycle.
 30. The laundry dryer of claim 28,further comprising a temperature sensor detecting the temperature of thelaundry and providing a temperature signal to the control deviceindicating the temperature of the laundry, the operating parameterincluding the temperature signal.
 31. The laundry dryer of claim 28,further comprising a electrodes detecting a moisture level of thelaundry and providing a moisture signal to the control device indicatingthe moisture level of the laundry, the operating parameter including themoisture signal.